This research study is to compare the effectiveness of a new drug, Uracil/Ftorafur (UFT) when given with the drug leucovorin (LV), to a standard treatment using a combination of the drugs 5-fluorouracil (5-FU) and LV in patients who have had a resection of their colon cancer. In previous studies where doctors thought they had removed all the colon cancer, a significant number of patients had a return of their cancer at a later time. Studies have shown that using chemotherapy after surgery can decrease the chance of cancer returning and can prolong the survival of the patients with tumors that invade through the bowel wall or that involve the lymph nodes in the area. The combination of two chemotherapy drugs, LV and 5-FU, has been shown to be effective for the treatment of colon cancer. UFT is a new investigational drug that has been found effective in their treating patients with advanced colon cancer.